The work for section Easy can be found in folder /Easy.
Manual-Chapter2-Walkthrough-And-Exercises.Rmd includes all source code, and Manual-Chapter2-Walkthrough-And-Exercises.html is the more-readable rendered html page.
The code includes the walk-through of example codes in Chapter2 of the manual. All exercises in the text and exercises at the end of the chapter are included as well, easier to find them with looking at the headings.
A rendered animint could be found at http://bl.ocks.org/Luna0618/raw/136edc11b06e4020dd6027a05dbf0e83/
The test for section medium can be found in folder /Medium.(unfinished)
least-squares.R includes the code for least squares model from https://yihui.org/animation/example/least-squares/.